I hate the new UI for gmail, (mobile and web) is the worst aberration in the history of google UIs. For example for web, now they hide the "from", "cc", "cco" fields, also they moved the reply, reply to all and forward to a drop down menu. The attach, and format buttons now are tiny and moved to the bottom. In the mobile they removed the check-boxes so when you want to select multiple mails you have to keep pressed a mail until it becomes blue and to select the other mails you have to tap where it used to be a check-box and if you mistakenly tap the title of the mail then your selection is lost and it opens that mail in a new view. They also hided the "from", "cc", "cco" fields in the mobile version. I seriously considering to use other clients.
>In the mobile they removed the check-boxes so when you want to select multiple mails you have to keep pressed a mail until it becomes blue and to select the other mails you have to tap
FYI, you can just tap on the email's avatar to select them. Maybe not the simplest interface, but it works well once you get used to it.